Assembly-Level Troubleshooting; Assembly-Level Troubleshooting; Power Supplies/Fan - HP 8340B Manual

Power Supplies/Fan
Assembly-Level Troubleshooting
WARNING
When the instrument is
connected
to
ac
line
power and/or the
A19
power-on safety indicator LED
is
on, there
are voltages present
inside
the instrument that can cause personal injury
or
death. Only qualified
personnel, who are aware of the hazards involved, should perform ser¬
vice
on this
instrument with
its
protective covers removed.
To
avoid non-repairable damage to assemblies,
do not reinstall the A19,
ASS, A52, or ASS
assemblies unless ac mains
is disconnected from the
instrument.
To protect static sensitive components, troubleshoot these assemblies
only at
a
work station equipped with an anti-static surface, and wear
a
grounding
strap.
When handling
a
printed circuit board, hold it
by the
edges; never
touch
the finger contacts.
INSTRUMENT BLOWS LINE FUSE
Initial Checks
1.
Ensure that the line
voltage selector cam is installed
in
the
line filter
module
with the
proper
voltage selected.
2.
Check that the proper
value fuse
is installed for the selected line
voltage.
Regulator Checks
1.
Remove
line
power and wait for
the A19 power-on safety indicator to go out.
2.
Remove the A52
regulator assembly.
3.
Reconnect
line
power
and turn on the instrument.
4.
If
the fuse blows, repeat the above procedure, removing, one
at
a
time, the ASS,
ASS, and
A19
assemblies.
5.
If
the fuse blows with all
these assemblies removed, suspect the A62 motherboard, or the
transformer itself.
6.
If
the line fuse does not blow after you remove one of the assemblies, replace or
troubleshoot
that assembly.
HP 8340B/41B
Power Supplies/Fan Assembly-Level Troubleshooting
1-9